diff --git a/lib/ace/ext/language_tools.js b/lib/ace/ext/language_tools.js
index 1d54d3b9..7133d740 100644
--- a/lib/ace/ext/language_tools.js
+++ b/lib/ace/ext/language_tools.js
@@ -39,8 +39,8 @@ var textCompleter = require("../autocomplete/text_completer");
 var keyWordCompleter = {
     getCompletions: function(session, pos, prefix, callback) {
         var keywords = session.$mode.$keywordList || [];
-        keywords.filter(function(w) {
-            return w.lastIndexOf(prefix, 0);
+        keywords = keywords.filter(function(w) {
+            return w.lastIndexOf(prefix, 0) == 0;
         });
         callback(null, keywords.map(function(word) {
             return {